Respiratory Case Study 7


When Charles returned to his apartment at 5 PM in the evening, he turned on his old kerosene-fueled space heater. It had been a cold day in late spring and his third floor apartment was chilly. After spending an hour fixing dinner, he ate while watching the evening news on TV. He noticed that his vision became progressively blurred. When he got up to go to the kitchen, he felt lightheaded and unsteady. Entering the kitchen, he became very disoriented and passed out. The next thing he remembered was waking up in the intensive care unit of the hospital. Some friends who had stopped by about 7 PM had found Charles unconscious on the kitchen floor. They had called an ambulance, which had rushed Charles, still unconscious, to the hospital.


Arterial Blood Data

pN2 = 573 mmHg

pO2 = 95  mmHg

pCO2 = 40 mmHg

pCO = 0.4 mmHg


1.) Describe the mechanics of breathing.  Include the relationship between pressure and volume.


2.) What structural features of normal lungs are necessary for good gas exchange?  Explain the role of partial pressure of gases in this exchange.


3.) Describe hemoglobinŐs role in both oxygen and carbon dioxide transport in the blood.


4.) The blood gas measurements show abnormalities in the partial pressure(s) of what gas(es)?


5.) Below is oxy-hemoglobin saturation curve in Charles blood (50% HbCO) and under normal conditions (2% HbCO).




6.) CO enhances the Bohr effect. Explain what this means.  Describe the observed change in the hemoglobin oxygen saturation curve.


7.) From the graph what is the approximate % saturation of hemoglobin by O2 in normal arterial blood?  What is the maximum amount of O2 (ml/ 100 ml blood) that can be carried in CharlesŐ arterial blood?


8.) What is the underlying cause of CharlesŐ condition?


9.) Discuss several potential treatment options for Charles.  What is his long-term prognosis?



adapted from ŇA Friend in Need is a Friend IndeedÓ by William H. Cliff, Niagara University and Ann W. Wright Canisius College

National Center for Science Teaching Using Case Studies